Composite sheets consisting of two metal cover sheets with a plastics layer arranged between the metal cover sheets, also called sandwich sheets, have an enormous weight-saving potential in comparison to the, for example, solid material steel sheets customarily used in motor vehicle manufacturing. For example, a sandwich sheet with a layer sequence of steel/plastic/steel and the following thicknesses of 0.5 mm/1 mm/0.5 mm has virtually the same bending properties in comparison to an identical monolithic variant with a thickness of 1.91 mm. However, the composite sheet or sandwich sheet has a weight which is up to 40% lower. In order to produce corresponding composite sheets, use has hitherto been made of laminating devices in the form of double belt presses which also comprise a laminating device. The metal strips provided for the metal cover sheets and the plastics film provided for the plastics layer are supplied continuously to the double belt press. In the double belt press, the metal strips and the plastics film are initially brought in a heating up zone to a laminating temperature before they are guided into a laminating device arranged within the double belt press. The laminating device which is arranged in the double belt press and is in the form of a calender produces the final adhesion between metal sheets and plastics layer by means of the high line pressure, followed by a cooling zone which is likewise formed by a double belt press and in which the strip-shaped composite sheet is cooled. Different cooling temperatures and cooling rates can be set in the cooling zone. In the double belt presses, the transport of heat both in the heating up zone and in the cooling zone takes place by direct or indirect contact with aluminum plates which move along at the belt speed or are arranged in a stationary manner. So that the surface of the composite sheet is not damaged, a transport belt which moves along is required between the stationary aluminum plates and the composite sheet. It has been shown that the production speeds of the corresponding, known device have hitherto been insufficient in order to obtain a high degree of economy in the production process. Furthermore, it is a constant requirement to increase the adhesion between metal sheets and plastics layer in order to prevent delamination between the metal layers and plastics layer, for example when further processing the composite sheets.
International patent application WO 2009/043777 A2 discloses a method for producing a composite sheet with two outer metal cover sheets and a plastics layer arranged between the cover sheets, in which, as explained, double belt presses are used for producing the composite sheet.